Collaborative Research: Type 1 - Improved Cold Region Hydrology Process Representation as a Cornerstone of Arctic Biogeochemical Modeling (L02170157)

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The Arctic is currently experiencing rapid environmental change, for example, widespread permafrost thaw and associated thermokarst initiation, changes in lake distribution, shifts in vegetation community composition, as well as changes in a host of other ecosystem processes. Threshold and non-linear responses associated with phase change between ice and water leave the Arctic particularly susceptible to swift and disruptive change. Realization of the scope of change, in conjunction with its pace, has spawned  concern that the massive and, until recently, effectively dormant soil carbon pools stored in permafrost-affected and peatland soils may be more vulnerable than previously thought. The fate of the Arctic carbon cycle is fundamentally governed by present and future soil hydrologic states.  There is an urgent need for the scientific community to be able to assess and quantify whether or not this carbon is an ?Arctic carbon time bomb?, as it is sometimes colloquially referred to, or if other biogeophysical and biogeochemical feedbacks will restrict or mitigate a substantial carbon release as permafrost thaws. Comprehensive Earth System Models (ESMs), such as the Community Earth System Model (CESM), are required to assess the integrated Arctic and global response to terrestrial Arctic change.  Though recent advances in the land model of CESM have been made with respect to the representation of permafrost, biogeochemical cycles, and Arctic vegetation succession, the current representation of cold region hydrology is inadequate to permit a holistic study of the Arctic permafrost carbon problem.  To address this limitation, we propose a targeted effort to improve Arctic terrestrial hydrological processes in the CESM and to use the resulting model to assess recent and future decadal-scale Arctic hydrology change.  The successful completion of this project will provide the foundation for a thorough evaluation of the Arctic terrestrial biogeochemical feedbacks.